1. Field of the Invention
The present invention relates to shielding systems for attenuating radiation energy from fluorescent imaging systems that employ radiation energy, especially for the protection of medical staff and patients against the damaging effects of x-rays and other similar high energy radiation used in surgical and other medical procedures.
2. The Relevant Technology
Physicians and allied clinical personnel, collectively referred to as medical staff, are commonly involved in medical procedures involving patients in which fluoroscopic and other types of radiation systems (such as computer tomography, or CT, systems) are used for purposes of diagnostic detection or guidance procedures. These radiation systems allow the medical staff to peer into the body systems of a patient with minimal invasiveness. The images generated may be in the form of a single image, or a video feed, both of which may be live. For example, the anatomy of a patient may be illuminated using x-rays so that the medical staff can carry out the procedures using a fluoroscopic viewing screen. In one case, x-ray fluoroscopy may be used to indirectly guide placement of a surgical device within the patient during the surgical procedure.
However, one of the concerns arising from the increased use of fluoroscopic radiation systems in medical procedures is the amount of radiation exposure to both medical staff and patients. Epidemiological data suggest that exposure to as “little” as 5 to 10 rem over a lifetime increases the risk of developing cancer. Literature also suggests that there is no lower threshold on the amount of radiation that could be considered acceptable. Further, studies have shown that elevated radiation exposure levels can be expected when larger body parts of a patient are imaged, or when parts of the medical staff's body, such as extremities, are positioned closer to the x-ray source or in the direct x-ray field.
While the exposure levels capable of producing damage to tissue are being debated and continually revised as more information is established, the cumulative effects of consistent radiation exposure remain unknown. That is, while the selected dose of radiation used in any one imaging sequence may normally be well below safe exposure limits, repeated exposure to medical staff and patients from one or more radiation sequences in procedures involving one or more patients may increase the risk of exposure for the medical staff and patients beyond what is normally considered safe operating procedures. This is possibly due to an increase in cumulative radiation dosage beyond what is normally considered safe. Recent investigations in medical diagnostics practices suggest that the dose and exposure should follow the “As Low As Reasonable” approach.
For instance, members of the surgical team may be exposed unnecessarily to x-rays when performing surgery on a patient involving the use of fluoroscopic imaging techniques. As an example, in diagnostic procedures using x-rays or computed tomography (CT) scans, a radiologist may have to hold a patient such as an infant, or an animal in the case of veterinary work, to restrain the movement of the patient in order to obtain satisfactory image resolution. In these cases, at a minimum, the hands of the radiologist or other medical staff may be exposed to harmful radiation, such as x-rays. Additionally, repeated exposure across multiple procedures on one or more patients may also increase the risk of radiation exposure to the medical staff.
The patient may also be exposed to increased risk as x-rays are used increasingly in more common doctor/patient settings. For example, mobile C-arm image intensifiers, as fluoroscopic imaging systems, are increasingly used in operating rooms, outpatient clinics, and emergency departments to image larger, denser body areas such as the pelvis or spine. The images are taken during elective and non-elective surgical procedures and may expose non-targeted bones and muscles to increased radiation, as well as other more radio-sensitive underlying visceral organs. Further, the same patient may be subject to multiple exposures over his or her life-time, thereby accumulating the dose and increasing the risks of harm to the patient.
As one solution, when possible lead aprons are used to protect both medical staff and patients from such radiation. These lead aprons are effective in blocking radiation incident to one side of the apron from going through the apron and exiting the other side, and as such protect whatever is underneath the apron from radiation. For instance, when imaging a targeted body part of a patient, one or more lead aprons may be arranged around the patient allowing exposure of the targeted body part, but at the same time minimizing radiation exposure of non-targeted body parts. Also, medical staff may wear lead aprons to protect themselves from radiation when the patient is subjected to fluoroscopic imaging.
However, these lead aprons can be heavy. Because this heaviness restricts movement of arms and hands of the medical staff, lead aprons worn by the medical staff typically leave the arms and hands free in order to perform the surgical procedure. As such, these lead aprons offer limited protection to the medical staff since their hands are exposed to repeated exposure.
Moreover, gloves containing lead compounds or other metals do not provide a satisfactory solution for reducing exposure to the hands and are not typically worn by the medical staff. These gloves may be inflexible or at increased risk for tearing. As a result, the lack of protection for the arms and hands of medical staff in repeated procedures may result in a cumulative radiation exposure that is above acceptable levels.
For instance, these gloves are made of a flexible polymer containing lead or lead compounds. They also may contain a layer of lead or lead compounds made by dipping the inner surface of a flexible glove into a mixture containing lead. These leaded gloves are suitable for blocking radiation. An alternative to lead are other heavy metals or heavy metal compounds comprising cadmium, tungsten and the like. However, these lead compounds and other heavy metal compounds are known to be toxic to human tissue. As such, gloves containing these lead compounds and other heavy metal compounds could leave trace amounts on the patient's skin or on the skin of the physician, just from the ordinary use of the glove. Moreover, the addition of lead or other heavy metal compounds of sufficient concentrations into the glove to block radiation may compromise the tear resistance of the glove. When the glove tears, these lead compounds or other heavy metal compounds within the glove may be exposed to the patient. In both of these cases, the use of these gloves may potentially result in the undesired assimilation of lead or other heavy metal compounds into the bodies of patients and medical staff.
Further, gloves infused with sufficient concentrations of lead to block radiation may be inflexible or stiff. This inflexibility restricts the agile movement of the physician's hand that is necessary for delicate procedures. That is, these gloves cause the physician's fingers to lose their dexterity. Moreover, this inflexibility of the gloves reduces the tactile sensation of the hands and fingers of the person wearing the glove. Physicians rely on this tactile sensation as a secondary source of information while simultaneously viewing the fluoroscopic viewing screen. For instance, tactile sensation is used by the physician to help guide their hands and fingers when they may be inside the patient and hidden from direct view.
Thus, a need exists to exercise caution and limit exposure to radiation for both medical staff and patients. It is also desirable to protect medical staff members from radiation in a way that does not limit them from conducting their procedures.